Resolution 7478 hazard mitigation

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2024 Hennepin County All -Jurisdiction Hazard Mitigation Plan Volume 2 — Hazard Inventory dust plumes. These storms can typically last 2-5 hours with winds from 53 to 78 mph. They produce the highest level of particle emission over a limited area, typically 2,000 to 6,000 square miles. The third type of dust storms are caused by tropical disturbances. These typically show strong concentration of dust in the air and last longer than frontal and meso- or small scale at 3-7 hours with wind speeds 30 to 58 mph. The typical area covered is just 200 to 4000 square miles. The last type of dust storm occurs from cyclogenesis which is the development of strengthening or a lower pressure area. Dust storms from cyclogenesis typically last longer than the others at 4-21 hours with wind speeds 38 to 65 mph because cyclogenesis tends to be stationary. These storms typically affect and area of 4000 to 31,000 square miles. 4.3.9.10. Detection & Warning As mentioned earlier, there is not a lot of indication for dust storms besides knowing the current conditions that may present the storm from occurring. However, with each of the types of dust storms mentioned above, there is never always a dust storm when those conditions are present. The National Weather Service in Chanhassen does not have a specific definition for when they would issue a blowing dust advisory or dust storm warning. In fact, The NWS Office in Chanhassen has never issued a blowing dust advisory or dust storm warning. However, the Grand Forks National Weather Service has. 4.3.9.11. Critical Values and Thresholds The blowing dust advisory conditions, visibilities at or below 1 mile, and dust storm warning, visibilities less than % mile, are the two critical values when it comes to warning the public for public safety concerns. Among those concerns are health concerns when dust particles are inhaled. The particles that are small enough to be inhaled are known as PM10 which are particulate matter less than 10 microns in size or smaller. 4.3.9.12. Mitigation The effects of sand and dust storms can be reduced by using several health & safety measures and environmental control strategies. Large-scale sand and dust storms are generally natural phenomena, and it may not be always practicable to prevent it happening. However, control measures can be taken to reduce its impacts. To reduce the consequences of dust events that may not reach dust storm criteria, cities can take appropriate control of dust raising factors such as increasing the vegetation cover where possible using native plants and trees as buffer. These can reduce wind velocity and sand drifts at the same time of increasing the soil moisture. Some health and safety measures that should be taken to minimize the adverse impacts due dust storms can be alerting vulnerable populations, using dust masks, and restricting outdoor activities and staying inside when dust storms are occurring. Mitigation strategies to reduce wind erosion from dust storms are lumped into two major categories: reduce the wind force at the soil surface and create a soil surface more resistant to wind forces. Some of these strategies are standing residues, planting perpendicular to prevailing winds, windbreaks, grass 157